This invention relates to irrigation systems and more particularly to an improved thrust block and coupling for use in irrigation systems.
It is well known to irrigate fields or to water golf courses or the like by means of a water distribution system which extends either underground throughout the course or over the field. The system typically includes PVC piping which extends throughout the field or the course and which is periodically interrupted by high pressure or high flow rate, low pressure valves. These valves are attached to the PVC pipe which is generally anywhere from 21/2 to 18 inches in diameter. Conventionally, the PVC pipe slides into a tight gasket of the valve to make a sealed gasketed connection. Specifically, a tapered end on the PVC pipe is forced into a tapered gasket or seal contained within the valve.
After the valve is attached to the PVC pipe, it is conventional to concrete the valve into a fixed underground location anywhere from 18 to 24 inches below ground level so as to prevent the valve from moving when water pressure is applied to the valve, as for example, when the valve is opened and closed. This concreting of the valve is referred to as "thrust" protection or a "thrust block" of the valve. In the absence of such thrust protection, each time the valve is opened or closed, there would be pressure acting upon the valve to try to move it in the ground and eventually become disconnected from the PVC pipe.
One problem with thrust protection as currently practiced in irrigation systems is that the valves are relatively inexpensive and regularly fail for a number of reasons, as for example, the packing inside of the valve fails and begins to leak, or the handle of the valve is twisted off or broken by an overly-enthusiastic technician. Currently, when the valve fails, a backhoe is typically brought in to dig a rather large hole to expose the concrete and the valve embedded therein. Once the backhoe has dug the large hole, the PVC pipe connected to the concreted-in valve is cut and the valve with the concrete is lifted from the hole. A new valve is then attached and extensions added to the existing PVC pipe to accommodate the new valve. More concrete is then poured into the hole around the valve for thrust protection of the new valve, the hole is filled back in and the surrounding ground repaired.
The current method of repairing broken valves having thrust protection within irrigation systems is very time consuming, damaging to the golf course or field, and demanding in that it requires a backhoe for digging out the concreted-in valve. Furthermore, the adjacent PVC pipe sections must be cut or severed in order to facilitate the repair of the valve and pipe extensions installed with the replacement valve further adding to the time, cost and expense of replacing a relatively inexpensive valve or part.